Morphology remarks: A medium-sized species of Zeugrhabdotus in which the inner cycle is bright, and opposite quadrants go into extinction together on rotation. A small, twisted bridge, composed of small blocks, spans the narrow, open central area.This form is smaller, and the inner cycle is broader, than in Z. sigmoides. The inner cycle is distinctively birefringent and the bar has a sigmoidal appearance similar to that seen in Z. sigmoides but dissimilar to other species of Zeugrhabdotus.

References:

Burnett, J. A. (1997c). New species and new combinations of Cretaceous nannofossils and a note on the origin of Petrarhabdus (Deflandre) Wise & Wind. Journal of Nannoplankton Research. 19(2): 133-146. gs :: view :: open